Pump-jet propeller rotor based on heterogeneous coupling blades and design method

Abstract

The invention provides a pump-jet propeller rotor based on heterogeneous coupling blades and a design method, the pump-jet propeller rotor comprises a plurality of groups of rotor blades which are arranged in a staggered coupling manner along the circumferential direction of a rotor hub, each group of rotor blades comprises long blades and short blades, the blade tip parts of each group of long blades are connected with the inner wall of a circular end ring, and the blade tip parts of each group of short blades are connected with the inner wall of the circular end ring; each group of short blades are arranged in a gap area between two adjacent long blades, and the blade root parts of the short blades are fixed on the inner wall of the circular end ring. When the scaling semi-suspension rudder is subjected to a loading test, torque application can be performed on the scaling semi-suspension rudder system, and the torque value of the rudder system can be monitored; and corresponding no-load test, static load test and dynamic load test are completed.

Description

Technical Field

[0001] The present application relates to the technical field of ship propulsion devices, and more specifically, to a pump-jet propulsor rotor based on heterogeneous coupled blades and a design method. Background Art

[0002] Modern ships have increasing requirements for ship propulsion devices, which not only require higher efficiency, but also require less vibration and lower noise. The research and development of low-noise ship propulsion devices has always been a hot topic for ship design and use departments at home and abroad. Among them, pump-jet propulsion devices are a type of ducted propulsion devices with front / rear stators. They have good propulsion, cavitation, operation stability and acoustic stealth, and are used in underwater vehicles and high-speed surface ships. However, the blade tip area between the rotor and the inner wall of the duct will inevitably produce complex gap flow, which is prone to tip gap cavitation and strong pressure pulsation, thus having a great negative impact on the overall propulsion performance, structural vibration and radiation noise characteristics of the propeller.

[0003] Although the current design methods such as rotor blade tip unloading and multi-blade design can increase the critical speed of the propeller, the blades are closely arranged at the root, and the resulting cascade effect and blade tip unloading reduce the propulsion efficiency of the propeller, making it difficult to meet the requirements of cavitation-free, high-efficiency and low-noise navigation at higher speeds in the future. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a pump-jet propeller rotor and design method based on heterogeneous coupled blades in response to the above-mentioned problems, which can significantly improve the critical speed of the propeller while reducing the propeller noise, and can be applied to the high-speed and low-noise design of various types of propeller rotors.

[0005] The embodiment of the present application is implemented as follows:

[0006] An embodiment of the present application provides a pump-jet propulsor rotor based on heterogeneous coupled blades, characterized in that it includes multiple groups of rotor blades arranged in an staggered coupling manner along the circumference of the rotor hub, each group of the rotor blades includes long blades and short blades, the blade tips of each group of long blades are connected to the inner wall of the circular end ring, and each group of short blades are arranged in the gap area between two adjacent long blades, and the blade roots of the short blades are fixed to the inner wall of the circular end ring.

[0007] In some optional embodiments, the blade tip of the short blade is located at the inner radius of the rotor and is not connected to the rotor hub.

[0008] In some optional embodiments, the circular end ring is embedded in the inner wall groove of the pump-jet thruster duct, and the inner surface of the circular end ring smoothly transitions to the inner wall surface of the duct.

[0009] In some optional embodiments, the chord length of the short blade at the blade root is longer than the chord length at the blade tip, and the chord length decreases from the blade root to the blade tip.

[0010] In some optional embodiments, a gap is provided between the outer wall surface of the circular end ring and the surface of the inner wall groove, and the gap distance does not exceed 10 mm.

[0011] A design method for a pump-jet propeller rotor based on heterogeneous coupled blades, characterized in that it comprises the following steps:

[0012] Step a, determine the rotor configuration:

[0013] The rotor blades are composed of two different types of blades, which are arranged in a staggered coupling along the circumference of the rotor hub. One type of rotor blade is longer in the radial direction, and the other type is shorter in the radial direction. The tip of the long blade is fixed to the circular end ring, and the root is fixed to the rotor hub. The root of the short blade is fixed to the circular end ring, and the tip is not connected to the rotor hub.

[0014] Step b, rotor blade design:

[0015] On the basis of determining the rotor blade configuration, according to the thrust, rotation speed and critical speed indicators of the propeller, determine the number of blades and load distribution characteristics, carry out rotor blade profile matching design according to the load, and complete the rotor blade design by adjusting the short blade profile and its relative position along the circumferential and axial directions relative to the long blade;

[0016] Step c, circular end ring design:

[0017] The circular end ring is embedded in the inner wall groove of the pump-jet propeller duct, and the inner surface of the circular end ring along the axial direction is kept in smooth transition with the inner wall surface of the duct, so as to realize the smooth flow of water inside the propeller;

[0018] Step d, calculation of propeller hydrodynamic performance:

[0019] After completing the rotor design, the computational fluid dynamics method is used to complete the hydrodynamic performance calculation of the propeller design scheme while considering the viscosity of the water flow, and to estimate the propeller efficiency, cavitation, and acoustic performance. Based on the calculation results, some design parameters are optimized and adjusted.

[0020] In some optional embodiments, the rotor blades adopt a NACA airfoil, and the blade shape values ​​of the long blades and the short blades are consistent in the range of 0.6D to 1.0D, D is the rotor diameter, and the chord length of the short blade decreases in a smooth transition form from 0.6D to a smaller radius, and is shortened to zero at a radius of 0.4D.

[0021] In some optional embodiments, the interval value of the axial position of the short blade relative to the long blade is 0 to 30% of the short blade chord length along the outflow direction. In the initial state of axial equal-angle distribution, the deflection toward the suction surface of the long blade does not exceed 20%*360 / N, where N is the number of rotor blades.

[0022] The beneficial effects of the present application are: 1. A pump-jet propeller rotor and design method based on heterogeneous coupled blades provided in the present application, by designing the structure of the blade coupling force unit, does not generate rotor blade tip vortex, can significantly increase the critical speed of the propeller while reducing the propeller noise; 2. The addition of end rings not only significantly reduces the wing grid blocking effect near the rotor hub, but also can achieve a further increase in the number of rotor blades without reducing efficiency, which is beneficial to the improvement of blade cavitation energy and noise performance; 3. It can be applied to the design of various types of high-efficiency, high-speed, low-noise water jet propulsion or pump-jet propulsion rotors, has a mature processing technology, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a schematic diagram of the structure of the propeller of an embodiment of the present application;

[0025] Figure 2 A front view of a propeller rotor according to an embodiment of the present application;

[0026] Figure 3 A cross-sectional view of a propeller according to an embodiment of the present application;

[0027] Figure 4 This is a comparison diagram of the open water characteristic curves of the thrusters of the embodiments of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0030] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0031] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0032] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0033] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0035] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0036] like Figure 1 , Figure 2 As shown, the present invention proposes a pump-jet propulsor rotor based on heterogeneous coupled blades, including multiple groups of rotor blades arranged in a staggered coupling manner along the circumference of a rotor hub 1, each group of rotor blades including long blades 2 and short blades 3, the blade tips of each group of long blades are connected to the inner wall of a circular end ring 4, each group of short blades are arranged in the gap area between two adjacent long blades, and the blade roots of the short blades are fixed to the inner wall of the circular end ring. The blade tips of the short blades are located at the inner radius of the rotor and are not connected to the rotor hub.

[0037] Adjacent long blades and short blades can form a group of blade-coupled force units. By adjusting the blade profile of the short blades and their relative position to the long blades, the blade group can produce favorable load coordination distribution and interference characteristics, and can suppress flow separation at the edge of the suction surface and reduce the overall unsteady excitation force of the rotor blades, thereby achieving the purpose of reducing vibration and noise.

[0038] like Figure 3 As shown, the circular end ring is embedded in the inner wall groove 6 of the pump-jet propeller duct 5, and the inner surface of the circular end ring smoothly transitions with the inner wall surface of the duct, thereby achieving smooth flow of water inside the propeller.

[0039] By adding circular end rings, not only can the blocking effect of the wing grid near the rotor hub be significantly reduced, the overall flow capacity and propulsion efficiency of the propeller can be increased, but also the number of rotor blades can be further increased without reducing efficiency, reducing the load on a single blade. The load on a single rotor blade is reduced, the force is more uniform, and it is beneficial to the improvement of the blade cavitation energy and noise performance.

[0040] There is a gap between the outer wall of the circular end ring and the surface of the inner wall groove, and the gap distance does not exceed 10mm. There is no longer a tip gap between the tip of the rotor blade and the duct, so the tip vortex cavitation is eliminated, and the outer radius of the rotor blade can adopt a larger chord length and pitch than the conventional rotor design, further improving the thrust of the propeller.

[0041] Furthermore, the chord length at the blade root of the short blade is longer than the chord length at the blade tip, and the chord length decreases from the blade root to the blade tip.

[0042] Example 1

[0043] In this embodiment, taking a front-stator type pump-jet propeller as an example, the rotor is arranged behind the propeller stator blades, and the propeller rotor is designed. The specific contents are as follows:

[0044] (1) Based on the propeller duct line shape and stator line shape, the rotor blade design is carried out. First, the rotor configuration is determined. The propeller rotor blades are composed of two different types of blades, which are staggered and coupled along the circumferential direction. There is a circular end ring at the outer radius (blade tip) of the rotor, which is connected to each blade. One type of rotor blade is longer in the radial direction, fixed to the rotor hub at the inner radius (blade root), and fixed to the circular end ring at the outer radius; the other type of rotor blade is shorter in the radial direction, fixed to the circular end ring at the inner radius, and is not connected to the rotor hub at the outer radius, shrinking to about 0.4D (D is the rotor diameter). A long blade and a short blade form a set of coupled force units.

[0045] (2) On the basis of determining the rotor blade configuration, the number of blades and load distribution characteristics are determined according to the thrust, rotational speed and critical speed indicators of the propeller. The rotor blade profile matching design is carried out according to the load. The rotor blade design is completed by adjusting the short blade profile and its relative position along the circumferential and axial directions relative to the long blade.

[0046] The rotor blades adopt NACA airfoils with good hydrodynamic performance. The blade profile values ​​of long blades and short blades are consistent in the range of 0.6D to 1.0D. The chord length of short blades decreases in a smooth transition form from 0.6D to a smaller radius, and shortens to zero at a radius of about 0.4D. The airfoil pitch and inclination of short blades are appropriately adjusted in the chord length contraction section to maintain a smooth transition of the flow state.

[0047] The interval value of the axial position of the short blade relative to the long blade is 0-30% of the short blade chord length along the outflow direction. In the initial state of axial equal angle distribution, the angle of deflection to the suction surface of the long blade does not exceed 20%*360 / N (N is the number of rotor blades) to suppress the flow separation at the edge of the suction surface of the long blade. The movement of the short blade along the axial direction can make the blade group produce strong load coordination, so as to achieve the purpose of reducing the overall excitation force of the rotor blade.

[0048] (3) Finally, the circular end ring design is completed. The circular end ring is embedded in the inner wall groove of the pump-jet propulsor duct, and the inner surface of the circular end ring along the axial direction is kept in a smooth transition with the inner wall surface of the duct to achieve smooth flow of water inside the propeller; a gap is provided between the outer wall surface of the circular end ring and the surface of the inner wall groove, and the gap distance does not exceed 10 mm.

[0049] (4) After completing the rotor design, the computational fluid dynamics method is used to complete the hydrodynamic performance calculation of the propeller design scheme under the condition of considering the viscosity of the water flow, estimate the propeller efficiency, cavitation, and acoustic performance, and optimize and adjust some design parameters based on the calculation results.

[0050] Under the same stator and duct design conditions, the hydrodynamic performance of the rotor design method and the conventional rotor blade design method was numerically simulated and analyzed. The open water efficiency was improved by an average of 5% in the range near the working point (see Figure 4 ); Under the self-propulsion condition of the vehicle, the amplitude of the first-order unsteady force is reduced by more than 50%, and the critical speed is increased by more than 8kn.

Claims

1. A pump-jet propeller rotor based on heterogeneous coupled blades, characterized in that: It comprises a plurality of groups of rotor blades which are arranged in an interlaced coupling manner along the circumference of the rotor hub, each group of the rotor blades comprises long blades and short blades, the blade tips of each group of long blades are connected to the inner wall of the circular end ring, each group of short blades are arranged in the gap area between two adjacent long blades, and the blade roots of the short blades are fixed to the inner wall of the circular end ring.

2. A pump-jet propeller rotor based on heterogeneous coupled blades according to claim 1, characterized in that: The blade tip of the short blade is located at the inner radius of the rotor and is not connected to the rotor hub.

3. A pump-jet propeller rotor based on heterogeneous coupled blades according to claim 2, characterized in that: The circular end ring is embedded in the inner wall groove of the pump-jet propeller conduit, and the inner surface of the circular end ring smoothly transitions to the inner wall surface of the conduit.

4. A pump-jet propeller rotor based on heterogeneous coupled blades according to claim 3, characterized in that: The chord length of the blade root of the short blade is longer than the chord length of the blade tip, and the chord length decreases from the blade root to the blade tip.

5. A pump-jet propeller rotor based on heterogeneous coupled blades according to claim 3 or 4, characterized in that: A gap is provided between the outer wall surface of the circular end ring and the surface of the inner wall groove, and the gap distance does not exceed 10 mm.

6. A design method for a pump-jet propeller rotor based on heterogeneous coupled blades according to claim 5, characterized in that: The steps include: Step a, determine the rotor configuration: The rotor blades are composed of two different types of blades, which are arranged in a staggered coupling along the circumference of the rotor hub. One type of rotor blade is longer in the radial direction, and the other type is shorter in the radial direction. The tip of the long blade is fixed to the circular end ring, and the root is fixed to the rotor hub. The root of the short blade is fixed to the circular end ring, and the tip is not connected to the rotor hub. Step b, rotor blade design: On the basis of determining the rotor blade configuration, according to the thrust, rotation speed and critical speed indicators of the propeller, determine the number of blades and load distribution characteristics, carry out rotor blade profile matching design according to the load, and complete the rotor blade design by adjusting the short blade profile and its relative position along the circumferential and axial directions relative to the long blade; Step c, circular end ring design: The circular end ring is embedded in the inner wall groove of the pump-jet propeller duct, and the inner surface of the circular end ring along the axial direction is kept in smooth transition with the inner wall surface of the duct, so as to realize the smooth flow of water inside the propeller; Step d, calculation of propeller hydrodynamic performance: After completing the rotor design, the computational fluid dynamics method is used to complete the hydrodynamic performance calculation of the propeller design scheme while considering the viscosity of the water flow, and to estimate the propeller efficiency, cavitation, and acoustic performance. Based on the calculation results, some design parameters are optimized and adjusted.

7. The design method of a pump-jet propeller rotor based on heterogeneous coupled blades according to claim 6 is characterized in that: The rotor blades adopt NACA airfoils, and the blade profile values ​​of long blades and short blades are consistent in the range of 0.6D to 1.0D, D is the rotor diameter, and the chord length of the short blade decreases in a smooth transition form from 0.6D to a smaller radius, and is shortened to zero at a radius of 0.4D.

8. The design method of a pump-jet propeller rotor based on heterogeneous coupled blades according to claim 7, characterized in that: The interval value of the axial position of the short blade relative to the long blade is 0 to 30% of the short blade chord length along the outflow direction. Under the initial state of axial equal-angle distribution, the angle of deflection toward the suction surface of the long blade does not exceed 20%*360 / N, where N is the number of rotor blades.

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